In the medical field, syringes (i.e., medical instruments for injection) are used in a variety of different ways.
For example, in a typical syringe, a female taper connector, such as a needle hub having a needle tube, is generally attached to a luer part located at the tip of syringes, and such syringes are used to draw blood from patients and to inject medication held in the syringes to patients.
In addition, syringes may be used in a system referred to as a pipeline system, such as a transfusion line system and a blood collection line system. In the pipeline system, a syringe is connected to an external port of the line system, and then medication in the syringe is applied therefrom, or reversely fluid is drawn from the line. To connect a syringe to such a line system, a direct connection method (also known as luer slip) and a fixed connection method are used. In the direct connection method, the luer part is inserted directly into the port of the line system. In the fixed connection method, a luer part 1141L of a syringe 1000L is connected to a port 1200L by screwing them together using a connector (lockout) 1130L, as shown in FIGS. 41A to 41C.
Prefilled syringes are also used in medical practices. Prefilled syringes are syringes containing prefilled medication in the syringe body. In this case, the nozzle tip of the syringe body is sealed by resin, for example, and the tip is opened before use and a plunger is inserted into the opening to thereby discharge the medication. Such prefilled syringes facilitate a rapid procedure by reducing the trouble and time required for administration of medication to patients and medication mixing.
As to syringes connectable to the port of the above-mentioned line system in a fixed manner (referred to as luer-lock syringes), it is often the case that a locknut is already attached to the luer part. A stepped portion, whose diameter is different from that of the rest of the luer part, is provided in the luer part. The luer part is preliminarily inserted into the locknut, which is kept in place by the stepped portion. This structure is adopted in order to reliably connect the syringe and the line system and enable a quick connection operation.
However, such a connector-attached syringe has a problem that the luer part cannot be connected to the direct connection port since the locknut is in the way, as shown in FIG. 42.
Another problem is that, when attempting to attach a needle hub to the connector-attached syringe at the luer part, the user cannot see the right positional relationship between the luer part and the needle hub since the lock nut is in the way, as shown in FIG. 43, and cannot connect the luer part and needle hub successfully. In addition, since the lockout is set on the luer part, the length of a portion of the luer part exposing outside is insufficient, which leads to a problem of not being able to make the needle hub adequately hold onto the luer part.
Thus, immediate improvement is desired in the versatility of lockout-attached syringes due to the requirements for speedy and accurate responses in medical field.